A computer program listing appendix containing the source code of a computer program that may be used with the present invention is incorporated herein by reference and appended hereto as one (1) original compact disk, and an identical copy thereof, containing a total of two (2) files as follows:
1. Field of the Invention
The present invention relates to telescopes, telescope mounts, and astronomical object locators. More particularly, the present invention relates to an altitude/azimuth telescope mount having an integral locator using magnetic encoders and a microprocessor for facilitating location of astronomical objects and telescope positioning for efficient and convenient observation of the objects.
2. Description of the Prior Art
Astronomers have long desired, and telescope manufacturers have long striven to develop, an effective but easy-to-use locator system for quickly and reliably locating astronomical objects and efficiently positioning a telescope for making observations thereof. The positions of astronomical objects are based upon a spherical coordinate system involving the perpendicular axes of right ascension and declination, determination of which requires a theodolite, a clock, and an accurate knowledge of the observer""s latitude and longitude. The theodolite is used to measure the object""s angle above the local horizon; the object""s declination is then calculated to be the angle between the Celestial Equatorial Plane (CEP) and the North Celestial Pole (NCP). An arbitrary 0xc2x0 longitudinal line has been defined as a line engraved on a brass plate set in the floor of the Old Royal Observatory in Greenwich, England.
The object""s right ascension requires a knowledge of the Local Sidereal Time, being based upon the moment of Local Sidereal Time the object transits the observer""s zenith, or local meridian. Because the Earth makes one full turn about its polar axis every twenty-four hours, right ascension is traditionally referred to in hours, from zero to twenty-four. Note, however, that right ascension is easily converted to degrees, with one hour of right ascension equaling 15xc2x0, or {fraction (1/24)} of a 360xc2x0 circle. Hours are further divided into finer units of 60 arcminutes, written 60xe2x80x2, or 3600 arcseconds, written 60xe2x80x3. A good telescope under good observing conditions can resolve details as fine as 1xe2x80x3 on the surface of the celestial sphere.
Having successfully mastered the complex spherical coordinate system, an astronomer is not yet ready to begin observation. Because the Earth""s axis of rotation moves, causing the coordinate grid to shift, an object""s right ascension and declination are continually changing. Thus, an object""s precise position is date dependent, with the current standard being equinox 2000.0, which means the object""s right ascension and declination at the moment the year 2000 began. For example, the star Vega (Alpha Lyra) currently may be found at approximately 18 h 37 m right ascension, and approximately +38 47xe2x80x2 declination.
As can be appreciated, locating astronomical objects and positioning a telescope for observation can be a difficult, frustrating, and time consuming process. Furthermore, once the telescope has been repositioned to observe a second object, a large part of the process must be inefficiently and inconveniently repeated to reacquire the first object.
Large institutional telescopes can be cost effectively equipped with computer-controlled automatic locator systems requiring only that the desired object""s right ascension and declination or its name or designation be entered, from which the computer can retrieve positioning data from a comprehensive database. Along with the time, date, and a knowledge of the fixed latitude and longitude of the observatory, the controlling computer can use drive motors to automatically position the telescope with positive feedback data provided by mechanical encoders.
Unfortunately, such automated systems are too expensive and cumbersome for use on small, portable telescopes. For example, common optical encoders for position determination are too expensive or use impractically complex or heavy mechanical gears or similar mechanisms. Furthermore, results of attempts to create a practical and economically feasible portable automated locator system for small telescopes have typically been sorely lacking in accuracy. Adding to the difficulty is the need to reduce weight and power consumption in order to preserve the portable nature of the telescope.
Due to these and other problems in the art, a need exists for an improved locator system.
The locator system of the present invention includes unique features that solve the above-identified and other problems by integrating the locator with the telescope mount in order to reduce weight and cost, and using magnetic encoders and a microprocessor to locate objects and provide position data with the degree of precision and accuracy necessary for many applications, including high magnification observation and astrophotography.
The mount is a portable azimuth-altitude mount providing two corresponding axes of rotation, with each axis having an associated encoder detecting and measuring movement of the telescope about the axis. Each encoder includes a ring of low cost ceramic permanently magnetic material suspended in a plastic matrix and presenting a plurality of poles, and a detector having a Hall-effect sensor operable to detect movement of the magnetic poles and to generate electrical data signals representative thereof. The microprocessor receives the data signals and translates them into position data for presentation via a display.
An advantage of the locator system is that no complex configuration process or calculations need be performed prior to or during use. Instead, the telescope need only be aligned with one or more reference objects whose positions are known to the microprocessor and based upon which the relative positions of other objects may be calculated. Another advantage of the system is that the microprocessor includes a catalog or database of objects and their positions, which can be recalled and displayed for the user. Yet another advantage of the locator system is that encoder data is translated into current position data which can be displayed, and which can be stored in the microprocessor""s memory. Thus, a user desiring to observe an object need only move the telescope until the displayed current position data matches the desired position data, thereby eliminating the inefficiency and inconvenience of having to determine or re-determine the object""s position based upon complex calculations.
These and other advantages of the present invention are further described in the section entitled DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT, below.